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      1 //===- MC/MCRegisterInfo.cpp - Target Register Description ----------------===//
      2 //
      3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
      4 // See https://llvm.org/LICENSE.txt for license information.
      5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
      6 //
      7 //===----------------------------------------------------------------------===//
      8 //
      9 // This file implements MCRegisterInfo functions.
     10 //
     11 //===----------------------------------------------------------------------===//
     12 
     13 #include "llvm/MC/MCRegisterInfo.h"
     14 #include "llvm/ADT/DenseMap.h"
     15 #include "llvm/ADT/Twine.h"
     16 #include "llvm/Support/ErrorHandling.h"
     17 #include <algorithm>
     18 #include <cassert>
     19 #include <cstdint>
     20 
     21 using namespace llvm;
     22 
     23 MCRegister
     24 MCRegisterInfo::getMatchingSuperReg(MCRegister Reg, unsigned SubIdx,
     25                                     const MCRegisterClass *RC) const {
     26   for (MCSuperRegIterator Supers(Reg, this); Supers.isValid(); ++Supers)
     27     if (RC->contains(*Supers) && Reg == getSubReg(*Supers, SubIdx))
     28       return *Supers;
     29   return 0;
     30 }
     31 
     32 MCRegister MCRegisterInfo::getSubReg(MCRegister Reg, unsigned Idx) const {
     33   assert(Idx && Idx < getNumSubRegIndices() &&
     34          "This is not a subregister index");
     35   // Get a pointer to the corresponding SubRegIndices list. This list has the
     36   // name of each sub-register in the same order as MCSubRegIterator.
     37   const uint16_t *SRI = SubRegIndices + get(Reg).SubRegIndices;
     38   for (MCSubRegIterator Subs(Reg, this); Subs.isValid(); ++Subs, ++SRI)
     39     if (*SRI == Idx)
     40       return *Subs;
     41   return 0;
     42 }
     43 
     44 unsigned MCRegisterInfo::getSubRegIndex(MCRegister Reg,
     45                                         MCRegister SubReg) const {
     46   assert(SubReg && SubReg < getNumRegs() && "This is not a register");
     47   // Get a pointer to the corresponding SubRegIndices list. This list has the
     48   // name of each sub-register in the same order as MCSubRegIterator.
     49   const uint16_t *SRI = SubRegIndices + get(Reg).SubRegIndices;
     50   for (MCSubRegIterator Subs(Reg, this); Subs.isValid(); ++Subs, ++SRI)
     51     if (*Subs == SubReg)
     52       return *SRI;
     53   return 0;
     54 }
     55 
     56 unsigned MCRegisterInfo::getSubRegIdxSize(unsigned Idx) const {
     57   assert(Idx && Idx < getNumSubRegIndices() &&
     58          "This is not a subregister index");
     59   return SubRegIdxRanges[Idx].Size;
     60 }
     61 
     62 unsigned MCRegisterInfo::getSubRegIdxOffset(unsigned Idx) const {
     63   assert(Idx && Idx < getNumSubRegIndices() &&
     64          "This is not a subregister index");
     65   return SubRegIdxRanges[Idx].Offset;
     66 }
     67 
     68 int MCRegisterInfo::getDwarfRegNum(MCRegister RegNum, bool isEH) const {
     69   const DwarfLLVMRegPair *M = isEH ? EHL2DwarfRegs : L2DwarfRegs;
     70   unsigned Size = isEH ? EHL2DwarfRegsSize : L2DwarfRegsSize;
     71 
     72   if (!M)
     73     return -1;
     74   DwarfLLVMRegPair Key = { RegNum, 0 };
     75   const DwarfLLVMRegPair *I = std::lower_bound(M, M+Size, Key);
     76   if (I == M+Size || I->FromReg != RegNum)
     77     return -1;
     78   return I->ToReg;
     79 }
     80 
     81 Optional<unsigned> MCRegisterInfo::getLLVMRegNum(unsigned RegNum,
     82                                                  bool isEH) const {
     83   const DwarfLLVMRegPair *M = isEH ? EHDwarf2LRegs : Dwarf2LRegs;
     84   unsigned Size = isEH ? EHDwarf2LRegsSize : Dwarf2LRegsSize;
     85 
     86   if (!M)
     87     return None;
     88   DwarfLLVMRegPair Key = { RegNum, 0 };
     89   const DwarfLLVMRegPair *I = std::lower_bound(M, M+Size, Key);
     90   if (I != M + Size && I->FromReg == RegNum)
     91     return I->ToReg;
     92   return None;
     93 }
     94 
     95 int MCRegisterInfo::getDwarfRegNumFromDwarfEHRegNum(unsigned RegNum) const {
     96   // On ELF platforms, DWARF EH register numbers are the same as DWARF
     97   // other register numbers.  On Darwin x86, they differ and so need to be
     98   // mapped.  The .cfi_* directives accept integer literals as well as
     99   // register names and should generate exactly what the assembly code
    100   // asked for, so there might be DWARF/EH register numbers that don't have
    101   // a corresponding LLVM register number at all.  So if we can't map the
    102   // EH register number to an LLVM register number, assume it's just a
    103   // valid DWARF register number as is.
    104   if (Optional<unsigned> LRegNum = getLLVMRegNum(RegNum, true))
    105     return getDwarfRegNum(*LRegNum, false);
    106   return RegNum;
    107 }
    108 
    109 int MCRegisterInfo::getSEHRegNum(MCRegister RegNum) const {
    110   const DenseMap<MCRegister, int>::const_iterator I = L2SEHRegs.find(RegNum);
    111   if (I == L2SEHRegs.end()) return (int)RegNum;
    112   return I->second;
    113 }
    114 
    115 int MCRegisterInfo::getCodeViewRegNum(MCRegister RegNum) const {
    116   if (L2CVRegs.empty())
    117     report_fatal_error("target does not implement codeview register mapping");
    118   const DenseMap<MCRegister, int>::const_iterator I = L2CVRegs.find(RegNum);
    119   if (I == L2CVRegs.end())
    120     report_fatal_error("unknown codeview register " + (RegNum < getNumRegs()
    121                                                            ? getName(RegNum)
    122                                                            : Twine(RegNum)));
    123   return I->second;
    124 }
    125